As(III) removal by hybrid reactive membrane process combined with ozonation

The removal of arsenite (As(III)) was investigated using a combined ozonation-reactive ceramic membrane incorporated with iron oxide nanoparticles (IONs). A disk-type γ-Al(2)O(3) ultrafiltration membrane (CM) was covered with IONs using an annealing method. The reactive ceramic membrane (RM) was then characterized using SEM, zeta potential measurements, and pure water permeability tests. The results showed that IONs were well attached on the RM surface. In addition, doped IONs had no significant effects on the pure water permeability and the isoelectric point (IEP) of RM. Laboratory-scale experiments were subsequently conducted to investigate the impact of combined RM and ozonation processes on As(III) rejection. The experimental results revealed that As(III) rejection rate of RM with an ozonation process (92%) significantly enhanced compared with that of CM (63%). The influence of operating parameters (i.e., pH, NOM, co-existing ions and temperature) revealed that an increase of pH, a decrease of temperature and presence of NOM led to a higher As(III) rejection, whereas the presence of co-existing ions in the feed water significantly reduced the As(III) rejection; divalent counter-ions were the greatest inhibitors for As(III) rejection. Finally, a comparison of As(III) rejection in synthetic water and real groundwater confirmed the importance of real conditions in the hybrid reactive membrane process with continuous ozonation.